The influence of Generalized Anxiety Disorder on Executive Functions in children with ADHD

The present study was aimed at verifying whether the presence of generalized anxiety disorder (GAD) affects executive functions in children with attention-deficit hyperactivity disorder (ADHD). Two groups of children with ADHD were selected for the study according to the presence or absence of GAD. The first group of 28 children with ADHD with GAD (mean age: 9 ± 1.2; males/females: 24/4) was matched for gender, age, IQ, psychiatric comorbidity with a second group of 29 children with ADHD without GAD (mean age: 8.8 ± 0.7; males/females: 26/3). The two groups with ADHD were compared to 28 typically developing children (mean age: 8.3 ± 1.3; males/females: 23/5) on different measures involving processes especially important in inhibitory control such as rule maintenance, stimulus detection, action selection and action execution. Our results indicated that, differently from children with ADHD with GAD, only the group with ADHD without GAD showed a deficit in inhibitory control. Comorbid subgroups should be differentiated, especially, to develop specific and efficient therapeutic interventions in ADHD.

Familiality of Co-existing ADHD and Tic Disorders: Evidence from a Large Sibling Study

Background: The association of attention-deficit/hyperactivity disorder (ADHD) and tic disorder (TD) is frequent and clinically important. Very few and inconclusive attempts have been made to clarify if and how the combination of ADHD+TD runs in families.

Aim: To determine the first time in a large-scale ADHD sample whether ADHD+TD increases the risk of ADHD+TD in siblings and, also the first time, if this is independent of their psychopathological vulnerability in general.

Methods: The study is based on the International Multicenter ADHD Genetics (IMAGE) study. The present sub-sample of 2815 individuals included ADHD-index patients with co-existing TD (ADHD+TD, n = 262) and without TD (ADHD–TD, n = 947) as well as their 1606 full siblings (n = 358 of the ADHD+TD index patients and n = 1248 of the ADHD-TD index patients). We assessed psychopathological symptoms in index patients and siblings by using the Strength and Difficulties Questionnaire (SDQ) and the parent and teacher Conners' long version Rating Scales (CRS). For disorder classification the Parental Account of Childhood Symptoms (PACS-Interview) was applied in n = 271 children. Odds ratio with the GENMOD procedure (PROCGENMOD) was used to test if the risk for ADHD, TD, and ADHD+TD in siblings was associated with the related index patients' diagnoses. In order to get an estimate for specificity we compared the four groups for general psychopathological symptoms.

Results: Co-existing ADHD+TD in index patients increased the risk of both comorbid ADHD+TD and TD in the siblings of these index patients. These effects did not extend to general psychopathology.

Interpretation: Co-existence of ADHD+TD may segregate in families. The same holds true for TD (without ADHD). Hence, the segregation of TD (included in both groups) seems to be the determining factor, independent of further behavioral problems. This close relationship between ADHD and TD supports the clinical approach to carefully assess ADHD in any case of TD.

Effects of Transcutaneous Electrical Nerve Stimulation (TENS) on Self-Efficacy and Mood in Elderly with Mild Cognitive Impairment

In previous studies, transcutaneous electrical nerve stimulation (TENS) has been applied to patients with either Alzheimer’s disease (AD) or incipient dementia, resulting in an enhancement in memory and verbal fluency. Moreover, affective behavior was shown to improve. Based on the positive effects of TENS in AD, it was hypothesized that TENS would improve self-efficacy in nondemented elderly with mild cognitive impairment (MCI) who live in a residential home. Four outcome measures, that is, a Dutch translation of the General Self-Efficacy Scale (Algemene Competentie Schaal), the Groninger Activity Restriction Scale, the Philadelphia Geriatric Center Morale Scale, and the Geriatric Depression Scale, were administered. Overall, the results suggest that the experimental group showed a mild improvement in self-efficacy and mood. In contrast, the placebo group showed a considerable reduction in self-efficacy and an increase in depression. Limitations of the present study and suggestions for future research are discussed.

Can the Children's Communication Checklist differentiate autism spectrum subtypes?

The study explored whether children with high functioning autism (HFA), Asperger syndrome (AS), and pervasive developmental disorder not otherwise specified (PDD-NOS) can be differentiated on the Children's Communication Checklist (CCC). The study also investigated whether empirically derived autistic subgroups can be identified with a cluster analytic method based on the Autism Diagnostic Interview–Revised. Fifty-seven children with HFA, 47 with AS, 31 with PDD-NOS, and a normal control group of 47 children between 6 and 13 years participated. Children with HFA,AS, and PDDNOS showed pragmatic communication deficits in comparison to the controls. Little difference was found between the three subtypes with respect to their CCC profile.A three-cluster solution explained the data best.The HFA cluster showed most autism characteristics, followed by the combined HFA + AS cluster, and then the PDD-NOS cluster. The findings support the autism spectrum concept based on severity of symptom impairment rather than distinct categories.

Neurofeedback for Attention-Deficit/Hyperactivity Disorder: Meta-Analysis of Clinical and Neuropsychological Outcomes From Randomized Controlled Trials

OBJECTIVE

We performed meta-analyses of randomized controlled trials to examine the effects of neurofeedback on attention-deficit/hyperactivity disorder (ADHD) symptoms and neuropsychological deficits in children and adolescents with ADHD.

METHOD

We searched PubMed, Ovid, Web of Science, ERIC, and CINAHAL through August 30, 2015. Random-effects models were employed. Studies were evaluated with the Cochrane Risk of Bias tool.

RESULTS

We included 13 trials (520 participants with ADHD). Significant effects were found on ADHD symptoms rated by assessors most proximal to the treatment setting, that is, the least blinded outcome measure (standardized mean difference [SMD]: ADHD total symptoms = 0.35, 95% CI = 0.11-0.59; inattention = 0.36, 95% CI = 0.09-0.63; hyperactivity/impulsivity = 0.26, 95% CI = 0.08-0.43). Effects were not significant when probably blinded ratings were the outcome or in trials with active/sham controls. Results were similar when only frequency band training trials, the most common neurofeedback approach, were analyzed separately. Effects on laboratory measures of inhibition (SMD = 0.30, 95% CI = -0.10 to 0.70) and attention (SMD = 0.13, 95% CI = -0.09 to 0.36) were not significant. Only 4 studies directly assessed whether learning occurred after neurofeedback training. The risk of bias was unclear for many Cochrane Risk of Bias domains in most studies.

CONCLUSION

Evidence from well-controlled trials with probably blinded outcomes currently fails to support neurofeedback as an effective treatment for ADHD. Future efforts should focus on implementing standard neurofeedback protocols, ensuring learning, and optimizing clinically relevant transfer.

Angiogenic, neurotrophic, and inflammatory system SNPs moderate the association between birth weight and ADHD symptom severity

Low birth weight is associated with increased risk for Attention-Deficit/Hyperactivity Disorder (ADHD); however, the etiological underpinnings of this relationship remain unclear. This study investigated if genetic variants in angiogenic, dopaminergic, neurotrophic, kynurenine, and cytokine-related biological pathways moderate the relationship between birth weight and ADHD symptom severity. A total of 398 youth from two multi-site, family-based studies of ADHD were included in the analysis. The sample consisted of 360 ADHD probands, 21 affected siblings, and 17 unaffected siblings. A set of 164 SNPs from 31 candidate genes, representing five biological pathways, were included in our analyses. Birth weight and gestational age data were collected from a state birth registry, medical records, and parent report. Generalized Estimating Equations tested for main effects and interactions between individual SNPs and birth weight centile in predicting ADHD symptom severity. SNPs within neurotrophic (NTRK3) and cytokine genes (CNTFR) were associated with ADHD inattentive symptom severity. There was no main effect of birth weight centile on ADHD symptom severity. SNPs within angiogenic (NRP1 & NRP2), neurotrophic (NTRK1 & NTRK3), cytokine (IL16 & S100B), and kynurenine (CCBL1 & CCBL2) genes moderate the association between birth weight centile and ADHD symptom severity. The SNP main effects and SNP × birth weight centile interactions remained significant after adjusting for multiple testing. Genetic variability in angiogenic, neurotrophic, and inflammatory systems may moderate the association between restricted prenatal growth, a proxy for an adverse prenatal environment, and risk to develop ADHD.

Candidate genetic pathways for attention-deficit/hyperactivity disorder (ADHD) show association to hyperactive/impulsive symptoms in children with ADHD

OBJECTIVE

Because multiple genes with small effect sizes are assumed to play a role in attention-deficit/hyperactivity disorder (ADHD) etiology, considering multiple variants within the same analysis likely increases the total explained phenotypic variance, thereby boosting the power of genetic studies. This study investigated whether pathway-based analysis could bring scientists closer to unraveling the biology of ADHD.

METHOD

The pathway was described as a predefined gene selection based on a well-established database or literature data. Common genetic variants in pathways involved in dopamine/norepinephrine and serotonin neurotransmission and genes involved in neuritic outgrowth were investigated in cases from the International Multicentre ADHD Genetics (IMAGE) study. Multivariable analysis was performed to combine the effects of single genetic variants within the pathway genes. Phenotypes were DSM-IV symptom counts for inattention and hyperactivity/impulsivity (n = 871) and symptom severity measured with the Conners Parent (n = 930) and Teacher (n = 916) Rating Scales.

RESULTS

Summing genetic effects of common genetic variants within the pathways showed a significant association with hyperactive/impulsive symptoms ((p)empirical = .007) but not with inattentive symptoms ((p)empirical = .73). Analysis of parent-rated Conners hyperactive/impulsive symptom scores validated this result ((p)empirical = .0018). Teacher-rated Conners scores were not associated. Post hoc analyses showed a significant contribution of all pathways to the hyperactive/impulsive symptom domain (dopamine/norepinephrine, (p)empirical = .0004; serotonin, (p)empirical = .0149; neuritic outgrowth, (p)empirical = .0452).

CONCLUSION

The present analysis shows an association between common variants in 3 genetic pathways and the hyperactive/impulsive component of ADHD. This study demonstrates that pathway-based association analyses, using quantitative measurements of ADHD symptom domains, can increase the power of genetic analyses to identify biological risk factors involved in this disorder.

Proactive and reactive control of movement are differently affected in Attention Deficit Hyperactivity Disorder children

Attention-Deficit/Hyperactivity Disorder children are impaired in the ability to interrupt an ongoing action in relation to a sudden change in the environment (reactive control, measured by stop signal reaction time, SSRT). Less investigated is the ability to control the response when it is known in advance that it will be required to stop (proactive control, measured by change in Reaction time, RT). The study is aimed at exploring both the reactive and the proactive inhibitory control in a group of ADHD children compared to a group of age-matched controls. ADHD children (N=28) and Controls (N=28) performed 4 tasks: 2 tasks required to respond to the appearance of the go-signals (go task and nostop task) and 2 tasks to respond to the go signals in a context in which sometimes a restrain or suppression of the response was required (go-nogo task and stop task). ADHD children showed a longer SSRT compared to controls. Both groups showed an increment in RT by comparing the go-nogo to the go task and an increment in RT and SD by comparing the stop to the nostop task. ADHD children showed higher intra-individual variability (SD) compared to controls only in the stop and nostop task. ADHD children showed impaired reactive control but preserved proactive control, and the physical appearance of the go signal affected their reaction times intra-individual variability. A comparison between the reactive and proactive controls helps in defining neuropsychological profiles of ADHD children and can inspires therapeutic behavioral-cognitive strategies for response control.

Stimulant treatment for attention-deficit hyperactivity disorder and risk of developing substance use disorder

BACKGROUND

Attention-deficit hyperactivity disorder (ADHD) is linked to increased risk for substance use disorders and nicotine dependence.

AIMS

To examine the effects of stimulant treatment on subsequent risk for substance use disorder and nicotine dependence in a prospective longitudinal ADHD case-control study.

METHOD

At baseline we assessed ADHD, conduct disorder and oppositional defiant disorder. Substance use disorders, nicotine dependence and stimulant treatment were assessed retrospectively after a mean follow-up of 4.4 years, at a mean age of 16.4 years.

RESULTS

Stimulant treatment of ADHD was linked to a reduced risk for substance use disorders compared with no stimulant treatment, even after controlling for conduct disorder and oppositional defiant disorder (hazard ratio (HR) = 1.91, 95% CI 1.10-3.36), but not to nicotine dependence (HR = 1.12, 95% CI 0.45-2.96). Within the stimulant-treated group, a protective effect of age at first stimulant use on substance use disorder development was found, which diminished with age, and seemed to reverse around the age of 18.

CONCLUSIONS

Stimulant treatment appears to lower the risk of developing substance use disorders and does not have an impact on the development of nicotine dependence in adolescents with ADHD.

Substance use disorders in adolescents with attention deficit hyperactivity disorder: a 4-year follow-up study

AIM

To examine the relationship between a childhood diagnosis of attention deficit hyperactivity disorder (ADHD) with or without oppositional defiant disorder (ODD)/conduct disorder (CD) and the development of later alcohol/drug use disorder [psychoactive substance use disorder (PSUD)] and nicotine dependence in a large European sample of ADHD probands, their siblings and healthy control subjects.

PARTICIPANTS, DESIGN AND SETTING

Subjects (n = 1017) were participants in the Belgian, Dutch and German part of the International Multicenter ADHD Genetics (IMAGE) study. IMAGE families were identified through ADHD probands aged 5-17 years attending out-patient clinics, and control subjects from the same geographic areas. After a follow-up period (mean: 4.4 years) this subsample was re-assessed at a mean age of 16.4 years.

MEASUREMENTS

PSUD and nicotine dependence were assessed using the Diagnostic Interview Schedule for Children, Alcohol Use Disorders Identification Test, Drug Abuse Screening Test and Fagerström test for Nicotine Dependence.

FINDINGS

The ADHD sample was at higher risk of developing PSUD [hazard ratio (HR) = 1.77, 95% confidence interval (CI) = 1.05-3.00] and nicotine dependence (HR = 8.61, 95% CI = 2.44-30.34) than healthy controls. The rates of these disorders were highest for ADHD youth who also had CD, but could not be accounted for by this comorbidity. We did not find an increased risk of developing PSUD (HR = 1.18, 95% CI = 0.62-2.27) or nicotine dependence (HR = 1.89, 95% CI = 0.46-7.77) among unaffected siblings of ADHD youth.

CONCLUSIONS

A childhood diagnosis of attention deficit hyperactivity disorder is a risk factor for psychoactive substance use disorder and nicotine dependence in adolescence and comorbid conduct disorder, but not oppositional defiant disorder, further increases the risk of developing psychoactive substance use disorder and nicotine dependence.

A behavioral neuroenergetics theory of ADHD

Energetic insufficiency in neurons due to inadequate lactate supply is implicated in several neuropathologies, including attention-deficit/hyperactivity disorder (ADHD). By formalizing the mechanism and implications of such constraints on function, the behavioral Neuroenergetics Theory (NeT) predicts the results of many neuropsychological tasks involving individuals with ADHD and kindred dysfunctions, and entails many novel predictions. The associated diffusion model predicts that response times will follow a mixture of Wald distributions from the attentive state, and ex-Wald distributions after attentional lapses. It is inferred from the model that ADHD participants can bring only 75-85% of the neurocognitive energy to bear on tasks, and allocate only about 85% of the cognitive resources of comparison groups. Parameters derived from the model in specific tasks predict performance in other tasks, and in clinical conditions often associated with ADHD. The primary action of therapeutic stimulants is to increase norepinephrine in active regions of the brain. This activates glial adrenoceptors, increasing the release of lactate from astrocytes to fuel depleted neurons. The theory is aligned with other approaches and integrated with more general theories of ADHD. Therapeutic implications are explored.

Neuropsychological correlates of emotional lability in children with ADHD

BACKGROUND

Emotional lability (EL) is commonly seen in patients with attention-deficit/hyperactivity disorder (ADHD). The reasons for this association remain currently unknown. To address this question, we examined the relationship between ADHD and EL symptoms, and performance on a range of neuropsychological tasks to clarify whether EL symptoms are predicted by particular cognitive and/or motivational dysfunctions and whether these associations are mediated by the presence of ADHD symptoms.

METHODS

A large multi-site sample of 424 carefully diagnosed ADHD cases and 564 unaffected siblings and controls aged 6-18 years performed a broad neuropsychological test battery, including a Go/No-Go Task, a warned four-choice Reaction Time task, the Maudsley Index of Childhood Delay Aversion and Digit span backwards. Neuropsychological variables were aggregated as indices of processing speed, response variability, executive functions, choice impulsivity and the influence of energetic and/or motivational factors. EL and ADHD symptoms were regressed on each neuropsychological variable in separate analyses controlling for age, gender and IQ, and, in subsequent regression analyses, for ADHD and EL symptoms respectively.

RESULTS

Neuropsychological variables significantly predicted ADHD and EL symptoms with moderate-to-low regression coefficients. However, the association between neuropsychological parameters on EL disappeared entirely when the effect of ADHD symptoms was taken into account, revealing that the association between the neuropsychological performance measures and EL is completely mediated statistically by variations in ADHD symptoms. Conversely, neuropsychological effects on ADHD symptoms remained after EL symptom severity was taken into account.

CONCLUSIONS

The neuropsychological parameters examined, herein, predict ADHD more strongly than EL. They cannot explain EL symptoms beyond what is already accounted for by ADHD symptom severity. The association between EL and ADHD cannot be explained by these cognitive or motivational deficits. Alternative mechanisms, including overlapping genetic influences (pleiotropic effects) and/or alternative neuropsychological processes need to be considered.

Aetiology for the covariation between combined type ADHD and reading difficulties in a family study: the role of IQ

BACKGROUND

Twin studies using both clinical and population-based samples suggest that the frequent co-occurrence of attention deficit hyperactivity disorder (ADHD) and reading ability/disability (RD) is largely driven by shared genetic influences. While both disorders are associated with lower IQ, recent twin data suggest that the shared genetic variability between reading difficulties and ADHD inattention symptoms is largely independent from genetic influences contributing to general cognitive ability. The current study aimed to extend the previous findings that were based on rating scale measures in a population sample by examining the generalisability of the findings to a clinical population, and by measuring reading difficulties both with a rating scale and with an objective task. This study investigated the familial relationships between ADHD, reading difficulties and IQ in a sample of individuals diagnosed with ADHD combined type, their siblings and control sibling pairs.

METHODS

Multivariate familial models were run on data from 1,789 individuals at ages 6-19. Reading difficulties were measured with both rating scale and an objective task. IQ was obtained using the Wechsler Intelligence Scales (WISC-III/WAIS-III).

RESULTS

Significant phenotypic (.2-.4) and familial (.3-.5) correlations were observed among ADHD, reading difficulties and IQ. Yet, 53%-72% of the overlapping familial influences between ADHD and reading difficulties were not shared with IQ.

CONCLUSIONS

Our finding that familial influences shared with general cognitive ability, although present, do not account for the majority of the overlapping familial influences on ADHD and reading difficulties extends previous findings from a population-based study to a clinically ascertained sample with combined type ADHD.

Categorical and Dimensional Definitions and Evaluations of Symptoms of ADHD: History of the SNAP and the SWAN Rating Scales

An earlier version of this article was originally submitted for publication in early 2000 to introduce a new dimensional of concept of Attention Deficit Hyperactivity Disorder (ADHD) provided by the Strengths and Weaknesses of ADHD-symptoms and Normal-behavior (SWAN) rating scale. The SWAN was developed to correct some obvious deficiencies of the Swanson, Nolan and Pelham (SNAP) rating scale that was based on the categorical concept of ADHD. The first submission was not accepted for publication, so a draft of the article was posted on a website (www.ADHD.net). The SWAN scale was published as a table in a review article (Swanson et al, 2001) to make it available to those interested in this dimensional approach to assessment of ADHD. Despite its relative inaccessibility, the SWAN has been used in several genetic studies of ADHD (e.g., Hay, Bennett, Levy, Sergeant, & Swanson, 2005; Cornish et al, 2005) and has been translated into several languages for European studies of ADHD (e.g., Lubke et al, 2006; Polderman et al, 2010) and into Spanish for studies in the United States (e.g., Lakes, Swanson, & Riggs, 2011; Kudo et al., this issue). Recently, invitations to include the SWAN in the PhenX Toolkit (www.phenx.org) for genomic studies (Hamilton et al, 2011) and to describe thedimensional approach of the SWAN for discussion of diagnostic (Swanson, Wigal, & Lakes, 2009) and ethical (Swanson, Wigal, Lakes, &Volkow, 2011) issues has convinced us that the unpublished article is still relevant after more than a decade, so it is presented here with some minor updates. We use examples (a) to document some consequences (e.g., over-identification of extreme cases) of using statistical cutoffs based on the assumption for a distribution of SNAP ratings that is highly skewed and (b) to show how the SWAN corrects the skewness of the SNAP by rewording the items on the scale and using a wider range of rating alternatives, which corrects the tendency to over-identify extreme cases.

The dopamine receptor D4 7-repeat allele influences neurocognitive functioning, but this effect is moderated by age and ADHD status: an exploratory study

OBJECTIVES

Evidence suggests the involvement of the dopamine D4 receptor gene (DRD4) in the pathogenesis of ADHD, but the exact mechanism is not well understood. Earlier reports on the effects of DRD4 polymorphisms on neurocognitive and neuroimaging measures are inconsistent. This study investigated the functional consequences of the 7-repeat allele of DRD4 on neurocognitive endophenotypes of ADHD in the Dutch subsample of the International Multicenter ADHD Genetics study.

METHODS

Participants were 350 children (5-11.5 years) and adolescents (11.6-19 years) with ADHD and their 195 non-affected siblings. An overall measure of neuropsychological functioning was derived by principal component analysis from five neurocognitive and five motor tasks. The effects of DRD4 and age were examined using Linear Mixed Model analyses.

RESULTS

The analyses were stratified for affected and non-affected participants after finding a significant three-way interaction between ADHD status, age and the 7-repeat allele. Apart from a main effect of age, a significant interaction effect of age and DRD4 was found in non-affected but not in affected participants, with non-affected adolescent carriers of the 7-repeat allele showing worse neuropsychological performance. In addition, carrying the 7-repeat allele of DRD4 was related to a significantly worse performance on verbal working memory in non-affected siblings, independent of age.

CONCLUSIONS

These results might indicate that the effect of the DRD4 7-repeat allele on neuropsychological functioning is dependent on age and ADHD status.

RD, ADHD, and their comorbidity from a dual route perspective

In order to achieve further insight into the comorbidity of reading disorder (RD) and attention deficit/hyperactivity disorder (ADHD), lexical processing and rapid naming were studied in RD and ADHD. The Dual Route Cascaded model postulates that lexical processing contains two parallel processes: lexical route processing and sublexical route processing. An orthographic decision task and a phonological decision task were used to measure lexical and sublexical route processing, respectively. In addition, a rapid naming task was used to compare 27 children with RD, 18 children with ADHD, 20 children with ADHD+RD, and 29 controls. RD and ADHD shared impairments in accuracy of orthographic and phonological decision making as well as in rapid naming, which suggest that RD and ADHD may be overlapping disorders that share deficits in both lexical route and sublexical route processing. RD was dissociated from ADHD by being slower in both orthographical and phonological decision making that indicates unique deficits in RD on lexical and sublexical speed.

CDH13 is associated with working memory performance in attention deficit/hyperactivity disorder

Different analytic strategies, including linkage, association and meta-analysis support a role of CDH13 in the susceptibility to attention deficit/hyperactivity disorder (ADHD). CDH13 codes for cadherin 13 (or H-cadherin), which is a member of a family of calcium-dependent cell-cell adhesion proteins and a regulator of neural cell growth. We tested the association between CDH13 on three executive functioning tasks that are promising endophenotypes of ADHD. An adjusted linear regression analysis was performed in 190 ADHD-affected Dutch probands of the IMAGE project. Three executive functions were examined: inhibition, verbal and visuo-spatial working memory (WM). We tested 2632 single nucleotide polymorphisms (SNPs) within CDH13 and 20 kb up- and downstream of the gene (capturing regulatory sequences). To adjust for multiple testing within the gene, we applied stringent permutation steps. Intronic SNP rs11150556 is associated with performance on the Verbal WM task. No other SNP showed gene-wide significance with any of the analyzed traits, but a 72-kb SNP block located 446 kb upstream of SNP rs111500556 showed suggestive evidence for association (P-value range 1.20E-03 to 1.73E-04) with performance in the same Verbal WM task. This study is the first to examine CDH13 and neurocognitive functioning. The mechanisms underlying the associations between CDH13 and the clinical phenotype of ADHD and verbal WM are still unknown. As such, our study may be viewed as exploratory, with the results presented providing interesting hypotheses for further testing.

ERPs associated with monitoring and evaluation of monetary reward and punishment in children with ADHD

BACKGROUND

Several models of attention-deficit hyperactivity disorder (ADHD) propose abnormalities in the response to behavioural contingencies. Using event-related potentials (ERPs), the present study investigated the monitoring and subsequent evaluation of performance feedback resulting in either reward or punishment in children with ADHD (N = 18) and normal controls (N = 18) aged 8 to 12 years.

METHODS

Children performed a time production task, in which visual performance feedback was given after each response. To manipulate its motivational salience, feedback was coupled with monetary gains, losses or no incentives.

RESULTS

Performance feedback signalling omitted gains as well as omitted losses evoked a feedback-related negativity (FRN) in control children. The FRN, however, was entirely absent in children with ADHD in all conditions. Moreover, while losses elicited enhanced amplitudes of the late positive potential (LPP) in controls, omitted rewards had this effect in ADHD.

CONCLUSIONS

The lack of modulation of the FRN by contingencies in ADHD suggests deficient detection of environmental cues as a function of their motivational significance. LPP findings suggest diminished response to punishment, but oversensitivity to the loss of desired rewards. These findings suggest that children with ADHD have problems assigning relative motivational significance to outcomes of their actions.

Pre-attentive processing in children with early and continuously-treated PKU. Effects of concurrent Phe level and lifetime dietary control

Sixty-four children, aged 7 to 14 years, with early-treated PKU, were compared with control children on visual evoked potential (VEP) amplitudes and latencies and auditory mismatch negativity (MMN) amplitudes. It was further investigated whether indices of dietary control would be associated with these evoked potentials parameters. There were no significant differences between controls and children with PKU in VEP- and MMN-indices. However, higher lifetime Phe levels were, in varying degree and stronger than concurrent Phe level, related to increased N75 amplitudes, suggesting abnormalities in attention, and longer P110 latencies, indicating a reduction in speed of neural processing, possibly due to deficits in myelination or reduced dopamine levels in brain and retina. Similarly, higher lifetime Phe levels and Index of Dietary Control (IDC) were associated with decreased MMN amplitudes, suggesting a reduced ability to respond to stimulus change and poorer triggering of the frontally mediated attention switch. In summary, the present study in children with PKU investigated bottom-up information processing, i.e., triggered by external events, a fundamental prerequisite for the individual's responsiveness to the outside world. Results provide evidence that quality of dietary control may affect the optimal development of these pre-attentive processes, and suggest the existence of windows of vulnerability to Phe exposure.

International variation in treatment procedures for ADHD: social context and recent trends

OBJECTIVE

Scientific and clinical interest in attention-deficit hyperactivity disorder (ADHD) is increasing worldwide. This article presents data from a cross-national workshop and survey related to questions of variability in diagnostic and, particularly, treatment procedures.

METHODS

Representatives of nine nations (Australia, Brazil, Canada, China, Germany, Israel, the Netherlands, Norway, and the United Kingdom), plus the United States, who attended a 2010 workshop on ADHD, responded to a survey that addressed diagnostic procedures for ADHD; treated prevalence of medication approaches, as well as psychosocial interventions; types of medications and psychosocial treatments in use; payment systems; beliefs and values of the education system; trends related to adult ADHD; and cultural and historical attitudes and influences related to treatment.

RESULTS

Use of both medication and psychosocial treatment for ADHD varies widely within and across nations. More expensive long-acting formulations of medications are becoming more widespread. Nations with socialized medical care provide a wide array of evidence-based interventions. Economic, historical, and political forces and cultural values are related to predominant attitudes and practices. Strong antipsychiatry and antimedication voices remain influential in many nations.

CONCLUSIONS

There is considerable variation in implementation of care for ADHD. Recognition of the social context of ADHD is an important step in ensuring access to evidence-based interventions for this prevalent, chronic, and impairing condition.

The impact of study design and diagnostic approach in a large multi-centre ADHD study: Part 2: Dimensional measures of psychopathology and intelligence

BACKGROUND

The International Multi-centre ADHD Genetics (IMAGE) project with 11 participating centres from 7 European countries and Israel has collected a large behavioural and genetic database for present and future research. Behavioural data were collected from 1068 probands with ADHD and 1446 unselected siblings. The aim was to describe and analyse questionnaire data and IQ measures from all probands and siblings. In particular, to investigate the influence of age, gender, family status (proband vs. sibling), informant, and centres on sample homogeneity in psychopathological measures.

METHODS

Conners' Questionnaires, Strengths and Difficulties Questionnaires, and Wechsler Intelligence Scores were used to describe the phenotype of the sample. Data were analysed by use of robust statistical multi-way procedures.

RESULTS

Besides main effects of age, gender, informant, and centre, there were considerable interaction effects on questionnaire data. The larger differences between probands and siblings at home than at school may reflect contrast effects in the parents. Furthermore, there were marked gender by status effects on the ADHD symptom ratings with girls scoring one standard deviation higher than boys in the proband sample but lower than boys in the siblings sample. The multi-centre design is another important source of heterogeneity, particularly in the interaction with the family status. To a large extent the centres differed from each other with regard to differences between proband and sibling scores.

CONCLUSIONS

When ADHD probands are diagnosed by use of fixed symptom counts, the severity of the disorder in the proband sample may markedly differ between boys and girls and across age, particularly in samples with a large age range. A multi-centre design carries the risk of considerable phenotypic differences between centres and, consequently, of additional heterogeneity of the sample even if standardized diagnostic procedures are used. These possible sources of variance should be counteracted in genetic analyses either by using age and gender adjusted diagnostic procedures and regional normative data or by adjusting for design artefacts by use of covariate statistics, by eliminating outliers, or by other methods suitable for reducing heterogeneity.

The impact of study design and diagnostic approach in a large multi-centre ADHD study. Part 1: ADHD symptom patterns

BACKGROUND

The International Multi-centre ADHD Genetics (IMAGE) project with 11 participating centres from 7 European countries and Israel has collected a large behavioural and genetic database for present and future research. Behavioural data were collected from 1068 probands with the combined type of attention deficit/hyperactivity disorder (ADHD-CT) and 1446 'unselected' siblings. The aim was to analyse the IMAGE sample with respect to demographic features (gender, age, family status, and recruiting centres) and psychopathological characteristics (diagnostic subtype, symptom frequencies, age at symptom detection, and comorbidities). A particular focus was on the effects of the study design and the diagnostic procedure on the homogeneity of the sample in terms of symptom-based behavioural data, and potential consequences for further analyses based on these data.

METHODS

Diagnosis was based on the Parental Account of Childhood Symptoms (PACS) interview and the DSM-IV items of the Conners' teacher questionnaire. Demographics of the full sample and the homogeneity of a subsample (all probands) were analysed by using robust statistical procedures which were adjusted for unequal sample sizes and skewed distributions. These procedures included multi-way analyses based on trimmed means and winsorised variances as well as bootstrapping.

RESULTS

Age and proband/sibling ratios differed between participating centres. There was no significant difference in the distribution of gender between centres. There was a significant interaction between age and centre for number of inattentive, but not number of hyperactive symptoms. Higher ADHD symptom frequencies were reported by parents than teachers. The diagnostic symptoms differed from each other in their frequencies. The face-to-face interview was more sensitive than the questionnaire. The differentiation between ADHD-CT probands and unaffected siblings was mainly due to differences in hyperactive/impulsive symptoms.

CONCLUSIONS

Despite a symptom-based standardized inclusion procedure according to DSM-IV criteria with defined symptom thresholds, centres may differ markedly in probands' ADHD symptom frequencies. Both the diagnostic procedure and the multi-centre design influence the behavioural characteristics of a sample and, thus, may bias statistical analyses, particularly in genetic or neurobehavioral studies.

The relationship between ADHD and key cognitive phenotypes is not mediated by shared familial effects with IQ

BACKGROUND

Twin and sibling studies have identified specific cognitive phenotypes that may mediate the association between genes and the clinical symptoms of attention deficit hyperactivity disorder (ADHD). ADHD is also associated with lower IQ scores. We aimed to investigate whether the familial association between measures of cognitive performance and the clinical diagnosis of ADHD is mediated through shared familial influences with IQ.

METHOD

Multivariate familial models were run on data from 1265 individuals aged 6-18 years, comprising 920 participants from ADHD sibling pairs and 345 control participants. Cognitive assessments included a four-choice reaction time (RT) task, a go/no-go task, a choice-delay task and an IQ assessment. The analyses focused on the cognitive variables of mean RT (MRT), RT variability (RTV), commission errors (CE), omission errors (OE) and choice impulsivity (CI).

RESULTS

Significant familial association (rF) was confirmed between cognitive performance and both ADHD (rF=0.41-0.71) and IQ (rF=-0.25 to -0.49). The association between ADHD and cognitive performance was largely independent (80-87%) of any contribution from etiological factors shared with IQ. The exception was for CI, where 49% of the overlap could be accounted for by the familial variance underlying IQ.

CONCLUSIONS

The aetiological factors underlying lower IQ in ADHD seem to be distinct from those between ADHD and RT/error measures. This suggests that lower IQ does not account for the key cognitive impairments observed in ADHD. The results have implications for molecular genetic studies designed to identify genes involved in ADHD.

Auditory conflict processing in ADHD

BACKGROUND

Impaired cognitive control has been implicated as an important developmental pathway to attention deficit/hyperactivity disorder (ADHD). Cognitive control is crucial to suppress interference resulting from conflicting information and can be measured by Stroop-like tasks. This study was conducted to gain insight into conflict processing in children with ADHD.

METHODS

Event-related potentials (ERPs) were recorded in an auditory Stroop task. Twenty-four children with ADHD were compared with 24 control children (aged 8-12 years).

RESULTS

No deficit in interference control was found on the auditory Stroop task in children with ADHD. Children with ADHD responded more slowly, less accurately and more variably compared to controls. No differences between the groups occurred in the early conflict-related ERPs. However, the difference between the congruent and the incongruent condition in the 450-550 ms time window was absent in the ADHD group compared to controls. In addition, the conflict sustained potential was found frontally in the ADHD group but parietally in the control group.

CONCLUSIONS

These ERP findings suggest that children with ADHD evaluate conflict to a lesser extent and differ in the way their brains select appropriate responses during conflict compared with controls.

Separation of cognitive impairments in attention-deficit/hyperactivity disorder into 2 familial factors

CONTEXT

Attention-deficit/hyperactivity disorder (ADHD) is associated with widespread cognitive impairments, but it is not known whether the apparent multiple impairments share etiological roots or separate etiological pathways exist. A better understanding of the etiological pathways is important for the development of targeted interventions and for identification of suitable intermediate phenotypes for molecular genetic investigations.

OBJECTIVES

To determine, by using a multivariate familial factor analysis approach, whether 1 or more familial factors underlie the slow and variable reaction times, impaired response inhibition, and choice impulsivity associated with ADHD.

DESIGN

An ADHD and control sibling-pair design.

SETTING

Belgium, Germany, Ireland, Israel, Spain, Switzerland, and the United Kingdom.

PARTICIPANTS

A total of 1265 participants, aged 6 to 18 years: 464 probands with ADHD and 456 of their siblings (524 with combined-subtype ADHD), and 345 control participants.

MAIN OUTCOME MEASURES

Performance on a 4-choice reaction time task, a go/no-go inhibition task, and a choice-delay task.

RESULTS

The final model consisted of 2 familial factors. The larger factor, reflecting 85% of the familial variance of ADHD, captured 98% to 100% of the familial influences on mean reaction time and reaction time variability. The second, smaller factor, reflecting 13% of the familial variance of ADHD, captured 62% to 82% of the familial influences on commission and omission errors on the go/no-go task. Choice impulsivity was excluded in the final model because of poor fit.

CONCLUSIONS

The findings suggest the existence of 2 familial pathways to cognitive impairments in ADHD and indicate promising cognitive targets for future molecular genetic investigations. The familial distinction between the 2 cognitive impairments is consistent with recent theoretical models--a developmental model and an arousal-attention model--of 2 separable underlying processes in ADHD. Future research that tests the familial model within a developmental framework may inform developmentally sensitive interventions.

Perinatal risk factors interacting with catechol O-methyltransferase and the serotonin transporter gene predict ASD symptoms in children with ADHD

BACKGROUND

Symptoms of autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD) often co-occur. Given the previously found familiality of ASD symptoms in children with ADHD, addressing these symptoms may be useful for genetic association studies, especially for candidate gene findings that have not been consistently replicated for ADHD.

METHODS

We studied the association of the catechol O-methyltransferase (COMT) Val158Met polymorphism and the serotonin transporter (SLC6A4/SERT/5-HTT) 5-HTTLPR insertion/deletion polymorphism with ASD symptoms in children with ADHD, and whether these polymorphisms would interact with pre- and perinatal risk factors, i.e., maternal smoking during pregnancy and low birth weight. Analyses were performed using linear regression in 207 Dutch participants with combined type ADHD of the International Multicenter ADHD Genetics (IMAGE) study, and repeated in an independent ADHD sample (n =439) selected from the TRracking Adolescents' Individual Lives Survey (TRAILS). Dependent variables were the total and subscale scores of the Children's Social Behavior Questionnaire (CSBQ).

RESULTS

No significant main effects of COMT Val158Met, 5-HTTLPR, maternal smoking during pregnancy and low birth weight on ASD symptoms were found. However, the COMT Val/Val genotype interacted with maternal smoking during pregnancy in increasing stereotyped behavior in the IMAGE sample (p =.008); this interaction reached significance in the TRAILS sample after correction for confounders (p =.02). In the IMAGE sample, the 5-HTTLPR S/S genotype interacted with maternal smoking during pregnancy, increasing problems in social interaction (p =.02), and also interacted with low birth weight, increasing rigid behavior (p =.03). Findings for 5-HTTLPR in the TRAILS sample were similar, albeit for related CSBQ subscales.

CONCLUSIONS

These findings suggest gene-environment interaction effects on ASD symptoms in children with ADHD.

Impaired decision making in oppositional defiant disorder related to altered psychophysiological responses to reinforcement

BACKGROUND

When making decisions, children with oppositional defiant disorder (ODD) are thought to focus on reward and ignore penalty. This is suggested to be associated with a state of low psychophysiological arousal.

METHODS

This study investigates decision making in 18 children with oppositional defiant disorder and 24 typically developing control subjects. Children were required to choose between three alternatives that carried either frequent small rewards and occasional small penalties (advantageous), frequent large rewards and increasing penalties (seductive), or frequent small rewards and increasing penalties (disadvantageous). Penalties in the seductive and disadvantageous alternatives increased either in frequency or magnitude in two conditions. Heart rate (HR) and skin conductance responses to reinforcement were obtained.

RESULTS

In the magnitude condition, children with ODD showed an increased preference for the seductive alternative (carrying large rewards); this was not observed in the frequency condition. Children with ODD, compared with typically developing children, displayed greater HR reactivity to reward (more HR deceleration) and smaller HR reactivity to penalty. Correlation analyses showed that decreased HR responses to penalty were related to an increased preference for large rewards. No group differences were observed in skin conductance responses to reward or penalty.

CONCLUSIONS

The findings suggest that an increased preference for large rewards in children with ODD is related to a reduced cardiac reactivity to aversive stimuli. This confirms notions of impaired decision making and altered reinforcement sensitivity in children with ODD and adds to the literature linking altered autonomic control to antisocial behavior.

Identifying loci for the overlap between attention-deficit/hyperactivity disorder and autism spectrum disorder using a genome-wide QTL linkage approach

OBJECTIVE

The genetic basis for autism spectrum disorder (ASD) symptoms in children with attention-deficit/hyperactivity disorder (ADHD) was addressed using a genome-wide linkage approach.

METHOD

Participants of the International Multi-Center ADHD Genetics study comprising 1,143 probands with ADHD and 1,453 siblings were analyzed. The total and subscale scores of the Social Communication Questionnaire (SCQ) were used as quantitative traits for multipoint regression-based linkage analyses on 5,407 autosomal single-nucleotide polymorphisms applying MERLIN-regress software, both without and with inclusion of ADHD symptom scores as covariates.

RESULTS

The analyses without ADHD symptom scores as covariates resulted in three suggestive linkage signals, i.e., on chromosomes 15q24, 16p13, and 18p11. Inclusion of ADHD symptom scores as covariates resulted in additional suggestive loci on chromosomes 7q36 and 12q24, whereas the LOD score of the locus on chromosome 15q decreased below the threshold for suggestive linkage. The loci on 7q, 16p, and 18p were found for the SCQ restricted and repetitive subscale, that on 15q was found for the SCQ communication subscale, and that on 12q for the SCQ total score.

CONCLUSIONS

Our findings suggest that QTLs identified in this study are ASD specific, although the 15q QTL potentially has pleiotropic effects for ADHD and ASD. This study confirms that genetic factors influence ASD traits along a continuum of severity, as loci potentially underlying ASD symptoms in children with ADHD were identified even though subjects with autism had been excluded from the IMAGE sample, and supports the hypothesis that differential genetic factors underlie the three ASD dimensions.

Eunethydis: a statement of the ethical principles governing the relationship between the European group for ADHD guidelines, and its members, with commercial for-profit organisations

The Eunethydis ADHD Guidelines group set out here the ethical principles governing the relationship between the group and industry. The principles set out here are provided to ensure that this is both done and seen to be done. The impetus for these guidelines comes from within the Group and is linked to the recognition for the need for an open and transparent basis for Group-industry relations, especially in the light of the present concern that the pharmaceutical industry may be exerting a growing influence on the actions of researchers and clinicians in the ADHD field.

To act or not to act, that's the problem: primarily inhibition difficulties in adult ADHD

Forty-nine carefully diagnosed adults with persistent attention deficit/hyperactivity disorder (ADHD), who had never been medicated for their ADHD, were compared with 49 normal control adults matched for age and gender on a large battery of tests in five domains of executive functioning (inhibition, fluency, planning, working memory, and set shifting) and several other neuropsychological functions to control for nonexecutive test demands. After stringent controls for nonexecutive function demands and IQ, adults with ADHD showed problems in inhibition and set shifting but not in any of the other executive functioning domains tested. We argue that adult ADHD may be mainly a disorder of inhibition.

Event-related potential correlates of selective processing in early- and continuously-treated children with phenylketonuria: effects of concurrent phenylalanine level and dietary control

This study focused on important characteristics of attentional (selective) processing in children with early-treated phenylketonuria (PKU). Seven to 14-year-old children with PKU were allocated to high phenylalanine (Phe) and low Phe groups and compared with control children on amplitudes and latencies of early and late event-related potential (ERP) components elicited during a selective processing task. These components are thought to measure early sensory processes (stimulus encoding/perception) and later selection processes (target detection). The effects of concurrent Phe level and dietary control on brain activity and behavioural performance were studied. Results showed that children with PKU with high Phe levels were less accurate and made more false alarms than controls and children with PKU with low Phe levels. Both children with PKU and controls displayed the expected early fronto-central selection negativity and a late positive peak over posterior sites associated with sensory aspects of the selective attention task. However, in contrast with controls, children with PKU showed an absence of condition differences for selection positivity over anterior sites associated with target detection. Negative and positive selection potentials over fronto-central sites were dependent on concurrent and historical Phe levels, whereas sensory potentials depended more strongly on historical Phe levels. It is concluded that both sensory and selection aspects of attention are affected by Phe levels. The relative predictive strength of historical Phe levels suggests that high Phe levels during sensitive periods for brain maturation may have long-lasting influences on selective attention.

How distinctive are ADHD and RD? Results of a double dissociation study

The nature of the comorbidity between Attention-Deficit/Hyperactivity Disorder (ADHD) and Reading Disability (RD) was examined using a double dissociation design. Children were between 8 and 12 years of age and entered into four groups: ADHD only (n = 24), ADHD+RD (n = 29), RD only (n = 41) and normal controls (n = 26). In total, 120 children participated in the study; 38 girls and 82 boys. Both ADHD and RD were associated with impairments in inhibition and lexical decision, although inhibition and lexical decision were more severely impaired in RD than in ADHD. Visuospatial working memory deficits were specific to children with only ADHD. It is concluded that there was overlap on lexical decision and to a lesser extent on inhibition between ADHD and RD. In ADHD, impairments were dependent on IQ, which suggest that the overlap in lexical decision and inhibition is different in origin for ADHD and RD. The ADHD only group was specifically characterized by deficits in visuospatial working memory. Hence, no double dissociation between ADHD and RD was found on executive functioning and lexical decision.

Differential effects of atomoxetine on executive functioning and lexical decision in attention-deficit/hyperactivity disorder and reading disorder

OBJECTIVE

The effects of a promising pharmacological treatment for attention-deficit/hyperactivity disorder (ADHD), atomoxetine, were studied on executive functions in both ADHD and reading disorder (RD) because earlier research demonstrated an overlap in executive functioning deficits in both disorders. In addition, the effects of atomoxetine were explored on lexical decision.

METHODS

Sixteen children with ADHD, 20 children with ADHD + RD, 21 children with RD, and 26 normal controls were enrolled in a randomized placebo-controlled crossover study. Children were measured on visuospatial working memory, inhibition, and lexical decision on the day of randomization and following two 28-day medication periods.

RESULTS

Children with ADHD + RD showed improved visuospatial working memory performance and, to a lesser extent, improved inhibition following atomoxetine treatment compared to placebo. No differential effects of atomoxetine were found for lexical decision in comparison to placebo. In addition, no effects of atomoxetine were demonstrated in the ADHD and RD groups.

CONCLUSION

Atomoxetine improved visuospatial working memory and to a lesser degree inhibition in children with ADHD + RD, which suggests differential developmental pathways for co-morbid ADHD + RD as compared to ADHD and RD alone.

CLINICAL TRIAL REGISTRY

B4Z-MC-LYCK, NCT00191906; http://clinicaltrials.gov/ct2/show/NCT00191906.

Pragmatics fragmented: the factor structure of the Dutch children's communication checklist (CCC)

BACKGROUND

A number of disorders are associated with pragmatic difficulties. Instruments that can make subdivisions within the larger construct of pragmatics could be important tools for disentangling profiles of pragmatic difficulty in different disorders. The deficits underlying the observed pragmatic difficulties may be different for different disorders.

AIMS

To study the construct validity of a pragmatic language questionnaire.

METHOD & PROCEDURES

The construct of pragmatics is studied by applying exploratory factor analysis (EFA) and confirmatory factor analysis to the parent version of the Dutch Children's Communication Checklist (CCC; Bishop 1998 ). Parent ratings of 1589 typically developing children and 481 children with a clinical diagnosis were collected. Four different factor models derived from the original CCC scales and five different factor models based on EFA were compared with each other. The models were cross-validated.

OUTCOMES & RESULTS

The EFA-derived models were substantively different from the originally proposed CCC factor structure. EFA models gave a slightly better fit than the models based on the original CCC scales, though neither provided a good fit to the parent data. Coherence seemed to be part of language form and not of pragmatics, which is in line with the adaptation of the CCC, the CCC-2 (Bishop 2003 ). Most pragmatic items clustered together in one factor and these pragmatic items also clustered with items related to social relationships and specific interests.

CONCLUSIONS & IMPLICATIONS

The nine scales of the original CCC do not reflect the underlying factor structure. Therefore, scale composition may be improved on and scores on subscale level need to be interpreted cautiously. Therefore, in interpreting the CCC profiles, the overall measure might be more informative than the postulated subscales as more information is needed to determine which constructs the suggested subscales are actually measuring.

Undertreatment of Motor Problems in Children with ADHD

BACKGROUND: Motor problems occur in 30% to 50% of children with ADHD, and have a severe impact on daily life. In clinical practice there seems to be little attention for this comorbidity with the possible consequence that these motor problems go undertreated. METHOD: Clinical interview and questionnaire survey of treatment by physiotherapy and factors predicting treatment of motor problems in 235 children with ADHD and 108 controls. RESULTS: Half of motor-affected children had received physiotherapy. Treated children had more severe motor problems, and less frequently presented with comorbid anxiety and conduct disorder. Treated and untreated children were similar in age, and rated similarly on ADHD inattentive and hyperactive-impulsive scales and parental socio-economic status. CONCLUSION: Currently, undertreatment of motor problems in ADHD occurs. Behavioural factors play a role in referral and intervention.

Does reward frequency or magnitude drive reinforcement-learning in attention-deficit/hyperactivity disorder?

Children with attention-deficit/hyperactivity disorder (ADHD) show an impaired ability to use feedback in the context of learning. A stimulus-response learning task was used to investigate whether (1) children with ADHD displayed flatter learning curves, (2) reinforcement-learning in ADHD was sensitive to either reward frequency, magnitude, or both, and (3) altered sensitivity to reward was specific to ADHD or would co-occur in a group of children with autism spectrum disorder (ASD). Performance of 23 boys with ADHD was compared with that of 30 normal controls (NCs) and 21 boys with ASD, all aged 8-12. Rewards were delivered contingent on performance and varied both in frequency (low, high) and magnitude (small, large). The findings showed that, although learning rates were comparable across groups, both clinical groups committed more errors than NCs. In contrast to the NC boys, boys with ADHD were unaffected by frequency and magnitude of reward. The NC group and, to some extent, the ASD group showed improved performance, when rewards were delivered infrequently versus frequently. Children with ADHD as well as children with ASD displayed difficulties in stimulus-response coupling that were independent of motivational modulations. Possibly, these deficits are related to abnormal reinforcement expectancy.

Effects of maternal and paternal smoking on attentional control in children with and without ADHD

Maternal smoking during pregnancy is a risk factor for attention-deficit/hyperactivity disorder (ADHD), but data on its adverse effects on cognitive functioning are sparse and inconsistent. Since the effect of maternal smoking during pregnancy may be due to correlated genetic risk factors rather than being a pure environmental effect, we examined the effect of prenatal exposure to smoking on attentional control, taking into account the effects of both maternal and paternal smoking, and examined whether these effects were genetically mediated by parental genotypes. We further examined whether the effect of prenatal exposure to smoking on attentional control interacted with genotypes of the child. Participants were 79 children with ADHD, ascertained for the International Multi-centre ADHD Gene project (IMAGE), and 105 normal controls. Attentional control was assessed by a visual continuous performance task. Three genetic risk factors for ADHD (DRD4 7-repeat allele of the exon 3 variable number of tandem repeats (VNTR), DAT1 10/10 genotype of the VNTR located in the 3' untranslated region, and the DAT1 6/6 genotype of the intron 8 VNTR) were included in the analyses. Paternal smoking had a negative effect on attentional control in children with ADHD and this effect appeared to be mediated by genetic risk factors. The prenatal smoking effect did not interact with genotypes of the child. Maternal smoking had no main effect on attentional control, which may be due to lower smoking rates. This study suggests that the effects of paternal smoking on attentional control in children with ADHD should be considered a proxy for ADHD and/or smoking risk genes. Future studies should examine if the results can be generalized to other cognitive domains.

Comorbid problems in ADHD: degree of association, shared endophenotypes, and formation of distinct subtypes. Implications for a future DSM

We aimed to assess which comorbid problems (oppositional defiant behaviors, anxiety, autistic traits, motor coordination problems, and reading problems) were most associated with Attention-Deficit/Hyperactivity Disorder (ADHD); to determine whether these comorbid problems shared executive and motor problems on an endophenotype level with ADHD; and to determine whether executive functioning (EF)-and motor-endophenotypes supported the hypothesis that ADHD with comorbid problems is a qualitatively different phenotype than ADHD without comorbid problems. An EF-and a motor-endophenotype were formed based on nine neuropsychological tasks administered to 816 children from ADHD-and control-families. Additional data on comorbid problems were gathered using questionnaires. Results indicated that oppositional defiant behaviors appeared the most important comorbid problems of ADHD, followed by autistic traits, and than followed by motor coordination problems, anxiety, and reading problems. Both the EF-and motor-endophenotype were correlated and cross-correlated in siblings to autistic traits, motor coordination problems and reading problems, suggesting ADHD and these comorbid problems may possibly share familial/genetic EF and motor deficits. No such results were found for oppositional defiant behaviors and anxiety. ADHD in co-occurrence with comorbid problems may not be best seen as a distinct subtype of ADHD, but further research is warranted.

PDD symptoms in ADHD, an independent familial trait?

The aims of this study were to investigate whether subtle PDD symptoms in the context of ADHD are transmitted in families independent of ADHD, and whether PDD symptom familiality is influenced by gender and age. The sample consisted of 256 sibling pairs with at least one child with ADHD and 147 healthy controls, aged 5-19 years. Children who fulfilled criteria for autistic disorder were excluded. The Children's Social Behavior Questionnaire (CSBQ) was used to assess PDD symptoms. Probands, siblings, and controls were compared using analyses of variance. Sibling correlations were calculated for CSBQ scores after controlling for IQ, ADHD, and comorbid anxiety. In addition, we calculated cross-sibling cross-trait correlations. Both children with ADHD and their siblings had higher PDD levels than healthy controls. The sibling correlation was 0.28 for the CSBQ total scale, with the CSBQ stereotyped behavior subscale showing the strongest sibling correlation (r = 0.35). Sibling correlations remained similar in strength after controlling for IQ and ADHD, and were not confounded by comorbid anxiety. Sibling correlations were higher in female than in male probands. The social subscale showed stronger sibling correlations in elder than in younger sibling pairs. Cross-sibling cross-trait correlations for PDD and ADHD were weak and not-significant. The results confirm that children with ADHD have high levels of PDD symptoms, and further suggest that the familiality of subtle PDD symptoms in the context of ADHD is largely independent from ADHD familiality.

White matter hyperintensities and working memory: an explorative study

White matter hyperintensities (WMH) are commonly observed in elderly people and may have the most profound effect on executive functions, including working memory. Surprisingly, the Digit Span backward, a frequently employed working memory task, reveals no association with WMH. In the present study, it was investigated whether more detailed analyses of WMH variables and study sample selection are important when establishing a possible relationship between the Digit Span backward and WMH. To accomplish this, the Digit Span backward and additional working memory tests, WMH subscores, and cardiovascular risk factors were examined. The results revealed that performance on the Digit Span backward test is unrelated to WMH, whereas a relationship between other working memory tests and WMH was confirmed. Furthermore, a division between several white matter regions seems important; hyperintensities in the frontal deep white matter regions were the strongest predictor of working memory performance.

Changes in neuropsychological functioning following temporal lobectomy in patients with temporal lobe epilepsy

PURPOSE

This study was conducted to evaluate the changes in neuropsychological functioning in patients with temporal lobe epilepsy (TLE) after temporal lobe resection.

METHODS

Fifty-four TLE patients were evaluated before and after surgery using comprehensive neuropsychological tests to assess general intelligence, executive functioning, language, verbal and visual memory, working memory, visuo-spatial ability, attention and motor function.

RESULTS

The patients with left TLE showed no impairment of neuropsychological functioning after surgery, with the exception of auditory immediate memory. Furthermore, they showed significant improvement in performance IQ, executive function, working memory, visual memory, attention and psychomotor speed. The patients with right TLE did not show any significant impairment in post-operative neuropsychological functioning. They showed improvements in intellectual and executive functions, language, visual memory, visuo-spatial ability, attention and motor function post-operatively. The patients with hippocampal sclerosis showed greater post-operative improvements than the patients without hippocampal sclerosis regardless of the side. Patients with better pre-operative neuropsychological function had a higher chance of successfully discontinuing all seizure medications after surgery.

DISCUSSION

The results of this study suggest that temporal lobectomy does not harm the neuropsychological functioning of patients with intractable TLE and that it improves cognitive functions of the contralateral hemisphere.

A review and analysis of the relationship between neuropsychological measures and DAT1 in ADHD

Meta-analyses indicate that the gene coding for the dopamine transporter (DAT1 or SLC6A3) is associated with an increased risk for ADHD. The mechanisms of this gene for ADHD are unclear. We systematically reviewed studies linking the VNTR in the 3' UTR of the DAT1 to neurophysiological and neuropsychological measures. In addition, a broad set of executive/cognitive and motor tests was administered to 350 children (5-11 years) and adolescents (11-19 years) with ADHD and 195 non-affected siblings. Two VNTRs (in intron 8 and the 3' UTR) and four SNPs (two 5' and two 3') in DAT1 were genotyped. The effect of the polymorphisms on neuropsychological functioning was studied. The review indicated that the majority of studies did not find a relation between DAT1 and neurophysiological or neuropsychological measures. In our sample, several of the polymorphisms of DAT1 were associated with ADHD and ADHD was associated with impaired neuropsychological functioning. However, none of the DAT1 polymorphisms was convincingly associated with neuropsychological dysfunctioning. This suggests that the effect of DAT1 on ADHD was not mediated by neuropsychological performance. However, since DAT1 is mainly expressed in the striatum and not the prefrontal cortex, it may influence striatum-related functions (such as delay aversion) more heavily than prefrontal related functions (such as executive functions). Associations of DAT1 with ADHD were only found in adolescents, which may suggest that DAT1 mainly exerts its effect in adolescence, and/or that having a more persistent form of ADHD may mark a more severe or homogeneous genetic form of the disorder.

Differential association between MAOA, ADHD and neuropsychological functioning in boys and girls

Attention-deficit/hyperactivity disorder (ADHD) is more common in boys than in girls. It has been hypothesized that this sex difference might be related to genes on the X-chromosome, like Monoamine Oxidase A (MAOA). Almost all studies on the role of MAOA in ADHD have focused predominantly on boys, making it unknown whether MAOA also has an effect on ADHD in girls, and few studies have investigated the relationship between MAOA and neuropsychological functioning, yet this may provide insight into the pathways leading from genotype to phenotype. The current study set out to examine the relationship between MAOA, ADHD, and neuropsychological functioning in both boys (265 boys with ADHD and 89 male non-affected siblings) and girls (85 girls with ADHD and 106 female non-affected siblings). A haplotype was used based on three single nucleotide polymorphisms (SNPs) (rs12843268, rs3027400, and rs1137070). Two haplotypes (GGC and ATT) captured 97% of the genetic variance in the investigated MAOA SNPs. The ATT haplotype was more common in non-affected siblings (P = 0.025), conferring a protective effect for ADHD in both boys and girls. The target and direction of the MAOA effect on neuropsychological functioning was different in boys and girls: The ATT haplotype was associated with poorer motor control in boys (P = 0.002), but with better visuo-spatial working memory in girls (P = 0.01). These findings suggest that the genetic and neuropsychological mechanisms underlying ADHD may be different in boys and girls and underline the importance of taking into account sex effects when studying ADHD.

Support for an independent familial segregation of executive and intelligence endophenotypes in ADHD families

BACKGROUND

Impairments in executive functioning (EF) and intelligence quotient (IQ) are frequently observed in children with attention deficit hyperactivity disorder (ADHD). The aim of this paper was twofold: first, to examine whether both domains are viable endophenotypic candidates for ADHD and second to investigate whether deficits in both domains tend to co-segregate within families.

METHOD

A large family-based design was used, including 238 ADHD families (545 children) and 147 control families (271 children). Inhibition, visuospatial and verbal working memory, and performance and verbal IQ were analysed.

RESULTS

Children with ADHD, and their affected and non-affected siblings were all impaired on the EF measures and verbal IQ (though unimpaired on performance IQ) and all measures correlated between siblings. Correlations and sibling cross-correlations were not significant between EF and IQ, though they were significant between the measures of one domain. Group differences on EF were not explained by group differences on IQ and vice versa. The discrepancy score between EF and IQ correlated between siblings, indicating that siblings resembled each other in their EF-IQ discrepancy instead of having generalized impairments across both domains. Siblings of probands who had an EF but not IQ impairment, showed a comparable disproportionate lower EF score in relation to IQ score. The opposite pattern was not significant.

CONCLUSIONS

The results supported the viability of EF and IQ as endophenotypic candidates for ADHD. Most findings support an independent familial segregation of both domains. Within EF, similar familial factors influenced inhibition and working memory. Within IQ, similar familial factors influenced verbal and performance IQ.

The influence of serotonin- and other genes on impulsive behavioral aggression and cognitive impulsivity in children with attention-deficit/hyperactivity disorder (ADHD): Findings from a family-based association test (FBAT) analysis

BACKGROUND

Low serotonergic (5-HT) activity correlates with increased impulsive-aggressive behavior, while the opposite association may apply to cognitive impulsiveness. Both types of impulsivity are associated with attention-deficit/hyperactivity disorder (ADHD), and genes of functional significance for the 5-HT system are implicated in this disorder. Here we demonstrate the separation of aggressive and cognitive components of impulsivity from symptom ratings and test their association with 5-HT and functionally related genes using a family-based association test (FBAT-PC).

METHODS

Our sample consisted of 1180 offspring from 607 families from the International Multicenter ADHD Genetics (IMAGE) study. Impulsive symptoms were assessed using the long forms of the Conners and the Strengths and Difficulties parent and teacher questionnaires. Factor analysis showed that the symptoms aggregated into parent- and teacher-rated behavioral and cognitive impulsivity. We then selected 582 single nucleotide polymorphisms (SNPs) from 14 genes directly or indirectly related to 5-HT function. Associations between these SNPs and the behavioral/cognitive groupings of impulsive symptoms were evaluated using the FBAT-PC approach.

RESULTS

In the FBAT-PC analysis for cognitive impulsivity 2 SNPs from the gene encoding phenylethanolamine N-methyltransferase (PNMT, the rate-limiting enzyme for adrenalin synthesis) attained corrected gene-wide significance. Nominal significance was shown for 12 SNPs from BDNF, DRD1, HTR1E, HTR2A, HTR3B, DAT1/SLC6A3, and TPH2 genes replicating reported associations with ADHD. For overt aggressive impulsivity nominal significance was shown for 6 SNPs from BDNF, DRD4, HTR1E, PNMT, and TPH2 genes that have also been reported to be associated with ADHD. Associations for cognitive impulsivity with a SERT/SLC6A4 variant (STin2: 12 repeats) and aggressive behavioral impulsivity with a DRD4 variant (exon 3: 3 repeats) are also described.

DISCUSSION

A genetic influence on monoaminergic involvement in impulsivity shown by children with ADHD was found. There were trends for separate and overlapping influences on impulsive-aggressive behavior and cognitive impulsivity, where an association with PNMT (and arousal mechanisms affected by its activity) was more clearly involved in the latter. Serotonergic and dopaminergic mechanisms were implicated in both forms of impulsivity with a wider range of serotonergic mechanisms (each with a small effect) potentially influencing cognitive impulsivity. These preliminary results should be followed up with an examination of environmental influences and associations with performance on tests of impulsivity in the laboratory.

A review on eye movement studies in childhood and adolescent psychiatry

The neural substrates of eye movement measures are largely known. Therefore, measurement of eye movements in psychiatric disorders may provide insight into the underlying neuropathology of these disorders. Visually guided saccades, antisaccades, memory guided saccades, and smooth pursuit eye movements will be reviewed in various childhood psychiatric disorders. The four aims of this review are (1) to give a thorough overview of eye movement studies in a wide array of psychiatric disorders occurring during childhood and adolescence (attention-deficit/hyperactivity disorder, oppositional deviant disorder and conduct disorder, autism spectrum disorders, reading disorder, childhood-onset schizophrenia, Tourette's syndrome, obsessive compulsive disorder, and anxiety and depression), (2) to discuss the specificity and overlap of eye movement findings across disorders and paradigms, (3) to discuss the developmental aspects of eye movement abnormalities in childhood and adolescence psychiatric disorders, and (4) to present suggestions for future research. In order to make this review of interest to a broad audience, attention will be given to the clinical manifestation of the disorders and the theoretical background of the eye movement paradigms.